Studies from this laboratory have shown that IL-1 acts directly on pituitary and adrenal cells (Alt-20) to stimulate ACTH and corticosterone secretion, respectively. In pituitary cells, we demonstrated that IL-1 stimulates ACTH secretion by activation of protein kinase A (PKA). Our studies demonstrate that IL-1 stimulates corticosterone release indirectly from the adrenal gland through adrenal medullary hormones. This was demonstrated in two in vitro systems rat adrenal organ cultures and primary rat adrenocortical cell cultures. The interaction between IL-1 and catecholamines is being studied to determine the intracellular mechanism of action of IL-1 on adrenal